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<H1>IBM Visualization Data Explorer Programmer&#39;s Reference</H1>
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<H3><A NAME="HDRDXGCMP" HREF="progu097.htm#PToC_254">DXGetCameraMatrix,
DXGetCameraRotation, DXGetCameraMatrixWithFuzz</A></H3>
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<P><STRONG>Function</STRONG>
<P>
Return matrices that represent stages of the viewing operation.
<P><STRONG>Syntax</STRONG>
<BR>
<TT><STRONG><BR>
&#35;include &lt;dx/dx.h&gt;<BR>
<P><BR>
Matrix DXGetCameraMatrix(Camera c)<BR>
Matrix DXGetCameraRotation(Camera c)<BR>
Matrix DXGetCameraMatrixWithFuzz(Camera c, float fuzz)<BR>
</STRONG></TT><BR>
<P><STRONG>Functional Details</STRONG>
<P>
A camera defines
the position and orientation of the viewer, the
volume of interest of the object being viewed, and the size of the
image to contain the resulting view.
<P>
Conceptually, there are three steps to converting an object in
3-dimensional space to an image in two-dimensional space:
<OL>
<P><LI>Translate the Object and camera as a unit so that
<TT><STRONG>
From
</STRONG></TT>
is at the center of the image, rotate them until
<TT><STRONG>
up
</STRONG></TT>
is aligned with the image
<TT><STRONG>
y
</STRONG></TT>
axis, and the
<TT><STRONG>
from-to
</STRONG></TT>
vector is perpendicular to the image.
<P>
<TT><STRONG>DXGetCameraRotation</STRONG></TT>, given camera
<TT><STRONG>c</STRONG></TT>,
returns the matrix that performs this series of transformations.
<P><LI>Scale the size of the volume of interest to the size of the
image.  (For additional details, see
<TT><STRONG>DXSetPerspective</STRONG></TT> and
<TT><STRONG>DXSetOrthographic</STRONG></TT>.)
<P>
<TT><STRONG>DXGetCameraMatrix</STRONG></TT>
and
<TT><STRONG>DXGetCameraMatrixWithFuzz</STRONG></TT>, given camera
<TT><STRONG>c</STRONG></TT>,
return the matrices that perform this step and the previous step.
<TT><STRONG>DXGetCameraMatrixWithFuzz</STRONG></TT>
returns the matrix with a given
<TT><STRONG>fuzz</STRONG></TT> applied.  The
<TT><STRONG>fuzz</STRONG></TT> allows an object that is coincident with a
second object, to be moved forward slightly to allow it to appear
in front of the second object.  An example of this would be displaying
contour lines on a surface; a positive
<TT><STRONG>fuzz</STRONG></TT> applied to the lines make the lines appear
displayed slightly in front of the surface.
<P><LI>For perspective cameras only, make the walls of the volume interest
parallel.  (For additional details, see
<TT><STRONG>DXSetPerspective</STRONG></TT>.)
</OL>
<P>
When these three steps are completed, the object has the
correct image x,y coordinates and can be rasterized.
<P><STRONG>Return Value</STRONG>
<P>
Return the matrix.
<P><STRONG>See Also</STRONG>
<P>
<TT><STRONG>
<A HREF="progu324.htm#HDRDXSRN">DXSetResolution, DXGetCameraResolution</A>,
<A HREF="progu328.htm#HDRDXSVW">DXSetView, DXGetView</A>,
<A HREF="progu246.htm#HDRDXNCA">DXNewCamera</A>,
<A HREF="progu319.htm#HDRDXSOC">DXSetOrthographic, DXGetOrthographic</A>,
<A HREF="progu323.htm#HDRDXSPE">DXSetPerspective, DXGetPerspective</A>,
<A HREF="progu292.htm#HDRDXRNDR">DXRender</A>
</STRONG></TT>
<P>
<A HREF="progu081.htm#HDRCAMSEC">16.7 , "Camera Class"</A>.
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